ReboundEmulator/TCPGameServer.cs

using System.Net.Sockets;
using System.Net;
using NotPogo.Core;
using NotPogo.Core.Rooms;

namespace NotPogo
{
    public class TCPGameServer(ILogger<TCPGameServer> logger, IConfiguration configuration) : BackgroundService
    {
        private readonly ILogger<TCPGameServer> _logger = logger;
        private readonly IConfiguration _configuration = configuration;

        private int _tcpPort;

        public TcpListener? Listener { get; private set; }

        public static List<TcpClient> Clients { get; } = [];
        public static BowlingGame? SingleplayerBowlingGame;

        static readonly HashSet<string> RoomOps = ["say", "rm.left", "disc", "gm.join"];

        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            _tcpPort = _configuration.GetValue<int>("GameServerPort");

            Listener = new(IPAddress.Any, _tcpPort);
            Listener.Start();
            _logger.LogInformation("Game Server Listening On Port {Port}", _tcpPort);

            while (!stoppingToken.IsCancellationRequested)
            {
                var client = await Listener.AcceptTcpClientAsync(stoppingToken);
                _logger.LogInformation("Client Connected: {RemoteEndPoint}", client.Client.RemoteEndPoint);
                _ = HandleClientAsync(client);
            }
        }

        private async Task HandleClientAsync(TcpClient client)
        {
            Player? player = null;

            using (client)
            await using (var stream = client.GetStream())
            {
                player = new(stream);
                try
                {
                    while (true)
                    {
                        Dictionary<string, string> received;
                        try
                        {
                            received = await TCPProtocol.ReadMessageAsync(stream);
                        }
                        catch (EndOfStreamException) { break; }

                        if (!received.TryGetValue("msg.op", out var op)) continue;
                        _logger.LogInformation("[plid {Plid}] <- {Op} {Fields}", 
                            player.Id, 
                            op, 
                            string.Join(" ", received.Where(kv => kv.Key != "msg.op").Select(kv => $"{kv.Key}='{kv.Value}'")));


                        if (op == "logn") // Login Request
                        {
                            // we know this is a compatible client now so let's add it to the client list
                            Clients.Add(client);

                            // handle logn
                            await HandleLoginAsync(player, received);
                        }
                        else if (op == "ping")
                        {
                            player.LastSeen = DateTime.UtcNow;
                        }
                        else if (player.Room is not null && (RoomOps.Contains(op) || op.StartsWith(player.Room.GameCode + ".")))
                        {
                            await player.Room.HandleAsync(player, op, received);
                        }
                        else if (op == "ext.over") // TODO: move to rooms extending IGameRoom
                        {
                            // because we aren't actually keeping track of anything going on in the games, we can just send the correct placeholders

                            bool isJackpot = (received["gm.won"] == "true") ? true : false;
                            int tokensWon = isJackpot ? Random.Shared.Next(0, 999) : 0;

                            await SendAsync(stream,
                                ("msg.op", "ext.rslt"),
                                ("tokb", "9999"),
                                ("tokn.won", isJackpot ? "100" : "0"),
                                ("spin.rslt", isJackpot ? "2" : "0"), // we aren't doing anything with the other outcomes so always issue tokens
                                ("spin.tokn", tokensWon.ToString()), // standalone reference implementation
                                ("inst.desc", ""),
                                ("jpot", "0"),
                                ("pzpm", ""),
                                ("bmlt", "1"),
                                ("bspo", "0"),
                                ("xpup", "0")
                            );

                            _logger.LogInformation("Results Sent");
                        }
                    }
                } catch (Exception e) when (e is EndOfStreamException or IOException or SocketException) { _logger.LogInformation("plid {Plid} disconnected ({Reason})", player.Id, e.GetBaseException().Message); }
                catch(Exception e)
                {
                    _logger.LogError(e, "Error Handling plid {Plid}", player.Id);
                }
                finally
                {
                    try
                    {
                        if (player.Room is { } room) await room.LeaveAsync(player);
                    }
                    catch(Exception e) { _logger.LogError(e, "Cleanup Failed For plid {Plid}", player.Id); }
                }
            }

            Clients.Remove(client);
            _logger.LogInformation("Client Disconnected");
        }

        private async Task HandleLoginAsync(Player player, Dictionary<string, string> logn)
        {
            var accnt = Sessions.Find(logn.GetValueOrDefault("lkey"));

            // populate player information
            player.Account = accnt;
            player.ScreenName = accnt?.ScreenName ?? $"Guest_{player.Id}";

            // get game code and rule id
            string game = logn.GetValueOrDefault("game", "");
            string rkey = logn.GetValueOrDefault("rkey", "");

            // pick the room
            var room = !string.IsNullOrEmpty(rkey) ? 
                RoomManager.Find(rkey) ?? 
                RoomManager.GetOrCreate(rkey, game) : 
                RoomManager.GetOrCreate($"{(game == "" ? "default" : game)}_lobby", game);

            string plid = player.Id.ToString();

            await player.SendAsync(
                ("msg.op", "logn"),
                ("flags", "65535"),
                ("time", DateTimeOffset.UtcNow.ToUnixTimeSeconds().ToString())
            );

            await player.SendAsync(
                ("msg.op", "init"),
                ("mxpl", "70"),
                ("plid", plid),
                ("mxtb", "70"),
                ("mxst", "4"),
                ("cnid", "1623")
            );

            await room.JoinAsync(player);
        }

        public static Task SendAsync(NetworkStream stream, params (string key, string value)[] fields)
        {
            var msg = new Dictionary<string, string>();
            foreach (var (key, value) in fields) msg[key] = value;
            return TCPProtocol.WriteMessageAsync(stream, msg);
        }

        static Dictionary<string, int> ParseInlineMap(string raw)
        {
            var result = new Dictionary<string, int>();
            if (string.IsNullOrEmpty(raw)) return result;

            var trimmed = raw.Trim('{', '}');
            foreach(var pair in trimmed.Split(','))
            {
                var kv = pair.Split('=');
                if(kv.Length != 2) continue;
                var key = kv[0].Trim();
                if (int.TryParse(kv[1].Trim(), out int value))
                    result[key] = value;
            }
            return result;
        }

        public override Task StopAsync(CancellationToken cancellationToken)
        {
            if(!cancellationToken.IsCancellationRequested)
            {
                Clients.Clear();
                Listener?.Stop();
                Listener?.Dispose();
            }

            return Task.CompletedTask;
        }
    }
}